Dicyclopentadiene (DCPD), which is represented by the following structural formula, is widely used as a starting material for the production of compounds such as ethylidene norbornene and cycloolefin polymer, and refined high-purity DCPD is needed depending on the intended application as the case may be.

Industrially, DCPD is produced by dimerizing cyclopentadiene contained in the C5 fraction of the pyrolysis product of naphtha. In this case, a step of separating the C5 fraction from the pyrolysis product, and facilities specialized for use for dimerizing the C5 fraction and others are needed.
As another method, for example, Patent Literature 1 U.S. Pat. No. 3,676,509 proposes a method for producing dicyclopentadiene in which method the C8 and higher fractions from a LPG cracking unit are pyrolyzed, and the high-purity cyclopentadiene obtained from the decomposition products is dimerized to yield dicyclopentadiene.
Additionally, as another method for producing high-purity DCPD, for example, Patent Literature 2 proposes a method in which cyclopentadiene contained in the C5 fraction obtained by pyrolysis of naphtha is dimerized into dicyclopentadiene, and thereafter, the dicyclopentadiene thus obtained is subjected to repeated distillations with a plurality of distillation towers.